GB1603149A

GB1603149A - Water-dispersible polyester resin solutions

Info

Publication number: GB1603149A
Application number: GB10892/78A
Authority: GB
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1977-03-25
Filing date: 1978-03-20
Publication date: 1981-11-18
Also published as: JPS569934B2; IT7821617A0; DE2810898A1; US4130520A; IT1096252B; FR2384807B1; CA1109578A; FR2384807A1; BE864842A; JPS53121095A

Description

PATENT SPECIFICATION ( 11) 1 603 149

{ ( 21) Application No 10892/78 ( 22) Filed 20 Mar 1978 ( 19) ( 31) Convention Application No 781260 ( 32) Filed 25 Mar 1977 in ( 33) United States of America (US) ( 44) Complete Specification Published 18 Nov 1981 ( 51) INT CL 3 C 09 D 3/64 ( 52) Index at Acceptance C 3 R 3 C 3 D 11 3 D 13 3 D 23 3 D 2 A 3 D 2 D 3 D 2 E 3 D 3 A 3 D 3 X 3 D 4 3 D 5 3 D 6 CII C 12 C 16 C 8 R L 5 C L 5 D L 5 X L 6 G SP C 3 Y B 240 B 243 H 220 ( 54) IMPROVEMEMTS IN OR RELATING TO WATER-DISPERSIBLE POLYESTER RESIN SOLUTIONS ( 71) We, WESTINGHOUSE ELECTRIC CORPORATION of Westinghouse Building Gateway Center Pittsburgh Pennsylvania United States of America, a corporation organised and existing under the laws of the Commonwealth of Pennsylvania, United States of America do hereby declare the invention, for which we prav that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the 5

following statement:-

This invention relates to a method of producing water-dispersible polyester resin solutions as well as to electrical conductors coated with such polyesters when in a cured condition.

Polyester coating compositions in solvent form are well known in the art These types of resin solutions pose fire and health hazards and are expensive U S Patent 3,310,512 10 (Curtice) solves the fire and health problems by teaching an aqueous coating system containing a water dispersible polyester resin having a low acid value.

Curtice reacted an aromatic dicarboxylic acid such as isophthalic acid with an aliphatic dicarboxylic acid such as adipic acid, and at least two polvols one of which must be hydrophilic, to impart water dispersibility to the final resin The hvdrophilic polyol is a 15 polyalkylene glycol such as polyethylene glycol and polyplene ene glycol The second polyol is selected from cyclic and aliphatic polyhydric alcohols such as neopentyl glycol, trimethylene glycol glycerol, trimethylol ethane and trimethylol propane The ratio of dicarboxylic acid: total polyol is 1:0 95 to 1 8, e e, OH/COOH = 0 95 to 1 8, providing a neutral or basic solution 20 In Curtice all of the reactants are added together and heated in an esterification process, until the acid value drops to below 30 This water soluble polyester is then added to a 98 % aqueous amine neutralizing solution, to form a polyester dispersion having a p H of about 7.

This dispersion can be cast as a wet film, dried, and baked at about 120 C, to provide hard, flexible films having good adhesion and solvent resistance properties These polyesters, while 25 providing a water dispersible system could, however, be improved in terms of increased water solubility, and improved thermal properties upon cure.

According to the present invention a method of producing a waterdispersible polyester resin solution comprises esterifying a mixture of ingredients consisting essentially of: (a) from 2 0 moles to 5 0 moles of an aromatic dicarboxvlic acid, tetrahydrophthalic acid and mixtures 30 thereof (b) from 0 1 mole to 1 5 moles of an organic, unsaturated aliphatic dicarboxylic acid, (c) from 0 1 mole to 6 5 moles of an organic saturated aliphatic dicarboxylic acid, (d) from 1 0 mole to 5 0 mole of an organic alicyclic dihydric alcohol (e) 0 mole to 5 0 moles of an organic, aliphatic dihydric alcohol, (f) from 0 3 mole to 1 2 moles of tris( 2-hydroxyalkyl)iso cyanurate where alkyl is from 2 to 6 carbon atoms or a polyhydric alcohol containing more 35 than two hydroxy groups per molecule and (g) an amount of organic solvent effective to provide a solution of from 50 wt % to 90 wt % solids content, and finally, diluting the polyester resin solution with a partially methylated melamine formaldehyde resin, and adding an organic aliphatic amine in an amount effective to provide a p H of from 8 to 9, wherein the esterification reaction is continued until the acid value drops to between 45 and 40 and wherein the mole ratio of OH/COOH = 0 30 to 0 90.

The invention also includes electrical conductors coated with polyester when made by the method of the last preceding paragraph and in a cured condition.

The above problems are countered by providing a water dispersible polyester resin solution, which contains an excess mole ratio of organic dicarboxylic acid over organic polyol, 45 2 1,603,149 2 and the inclusion of a large percentage of organic cyclic polyols Preferably, there is a dual reaction sequence and the reaction is continued until the acid value is between 45 and 65.

This provides an excess of available acid, with resulting excellent water solubility, and use of major amounts of alicyclic alcohol, with resulting improved thermal properties Major amounts of relatively water insoluble dicarboxylic acid, such as isophthalic acid, and 5 relatively water insoluble alicyclic alcohols, such as 1-4 cyclohexanedimethanol are included in the reaction product, by deliberately maintaining an acidic environment, i e, maintaining a mole ratio of OH/COOH of below 0 90.

This definite acidic environment is maintained and a two-step reaction sequence is preferably followed A major amount of an organic, dicarboxylic acid, such as isophthalic 10 acid and tetrahydrophthalic anhydride, and a small amount of an organic, unsaturated aliphatic dicarboxylic acid, such as maleic anhydride, is added to an organic, alicyclic dihydric alcohol, such as 1-4 cyclohexane dimethanol These reactants are added together and then heated in an esterification process at a temperature of between about 180 C to 250 C, for 1/2 to 4 hours, until the acid value drops to between about 45 to 65 Then, an organic, saturated 15 aliphatic dicarboxylic acid, such as adipic acid, is added to provide a flexible product The esterification reaction is continued at about 180 C to 250 C, for 5 to 10 hours, and the acid value maintained between 45 and 65, preferably from 50 to 60.

The mole ratio of dicarboxylic acid:total polyol must be from 1:0 30 to 0 90, i e, OH/COOH = 0 30 to 0 90, providing an acidic condition Aqueous melamineformaldehyde 20 solution is added, to finally dilute the polyester and to form a polyester dispersion of about 60 wt.% solids content Then, the p H is adjusted to from 8 to 9, and the dispersion is made completely water soluble, by the addition of an effective amount of an aliphatic organic amine The formulations, having a viscosity of between 4,000 cps to 20,000 cps at 25 C, were found to be infinitely soluble in water They were easily coatable and castible to form 25 solid low temperature curing films The films could be coated onto a wide variety of electrical conductors or substrates, to provide insulation having excellent heat resistance at up to about C (class H), low weight loss, and high bond strength.

In the method of this invention, from 2 0 moles to 5 0 moles of a dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids and tetrahydrophthalic acid or 30 anhydride, and mixtures thereof, and from 0 1 mole to 1 5 moles of an unsaturated aliphatic dicarboxylic acid are added to from 1 0 mole to about 5 0 moles of an alicyclic, dihydric alcohol and 0 mole to about 5 0 moles, preferably about 0 1 mole to about 5 0 moles, of an aliphatic dihydric alcohol Generally, from 0 3 mole to 1 2 moles of a suitable organic branching agent effective to cross link the acids and alcohols is added, along with an effective 35 amount of a saturated aliphatic dicarboxylic acid, and an esterification reaction is conducted.

Then the mixture is reduced to from 50 wt % to 90 wt %, and preferably from 75 wt % to 85 wt.%, solids, with a suitable organic solvent having a high boiling point.

The esterification reaction is generally conducted, in a suitable reaction vessel containing all the ingredients except the saturated aliphatic dicarboxylic acid, at a temperature of 40 between 180 C and 250 C, for a time effective to drop the acid value to between 45 and 60, generally from 1/2 to 4 hours The reaction mixture is then generally cooled to between 135 and 160 C, and from 0 1 mole to 6 5 moles of a saturated aliphatic dicarboxylic acid is added as the last ingredient, to provide flexibility in the cured reaction product The reaction is continued at a temperature of from 180 C to 250 C, for a time effective to drop the acid value 45 to between 45 to 65, and preferably from 50 to 60, generally from 5 to 10 hours, to form a polyester resin to which organic solvent is added to form a solution.

The polyester resin solution is then added to a melamine formaldehyde solution to provide an aqueous polyester dispersion of from 50 wt % to 70 wt % solids The p H of the polyester is adjusted to from 8 to 9, and the polyester is made infinitely soluble in the water by addition of 50 an effective amount of an organic aliphatic amine The final OH/COOH mole ratio will range from 0 30 to 0 90 The viscosity of the final solution will range from 4, 000 cps to 20,000 cps.

at 25 C.

Suitable dicarboxylic acids include aromatic dicarboxylic acids for example, phthalic acid; isophthalic acid; and terephthalic acid and tetrahydrophthalic acid their anhydrides and their 55 mixtures where the term "acid" is also meant to include corresponding anhydrides Suitable unsaturated aliphatic dicarboxylic acids include, for example, maleic acid; and fumaric acid, their anhydrides and their mixtures Suitable alicyclic, dihydric alcohols include, for example, 1,4-cyclohexane dimethanol; 1,2-cyclopentane diol and 1,2cyclohexane diol and their mixtures Suitable aliphatic dihydric alcohols include, for example, neopentyl glycol; 60 ethylene glycol; propylene glycol; 1,3-propane diol; 1,2-butane diol; and 1,4-butane diol.

Suitable saturated aliphatic dicarboxylic acids include, for example, adipic acid; succinic acid; glutaric acid; pimelic acid; suberic acid; azelaic acid and sebacic acid, their anhydrides and their mixtures.

Useful compounds effective to help cross linking during the esterification reaction include, 65 1,603,149 1,603,149 for example, tris ( 2 hydroxy alkyl) isocyanurate, where alkyl is from 2 to 6 carbons, particularly tris ( 2 hydroxy ethyl) isocyanurate, and organic polyhydric alcohols containing more than two hydroxl groups per molecule, such as trimethylol propane; glycerol; pentaerythritol; dipenterythritol; trimethylol ethane; sorbitol; erythritol; and inositol and their mixtures Suitable organic solvents include, for example, ethylene glycol monoalkyl 5 ethers, such as glycol monobutyl ether (butyl "Cellosolve") and diethylene glycol monobutyl ether (butyl "Carbitol"); ethylene glycol monoacetate; ketones and glycols and their mixtures, having flash points over 150 C Preferred solvents are butyl "Cellosolve" and butyl "Carbitol" "Cellosolve" and "Carbitol" are Registered Trade Marks.

These are reacted and then diluted with a partially methylated melamine formaldehyde 10 resin effective to improve the gel time of the final solution, such as hexamethoxymethyl melamine The diluted polyester dispersion is finally p H adjusted, and made completely water soluble by the addition of an effective amount of an organic aliphatic amine such as triethanol amine; triethylamine; 2 amino-2-methyl-1 propanol and dimethylamino-2-methyl1 propanol and dimethylethanol amine and their mixtures 15 The invention will now be illustrated with reference to the following Examples 1 to 3:

EXAMPLE 1

A water dispersible polyester insulating resin was made by adding 2 3 moles ( 390 grams) of isophthalic acid (aromatic dicarboxylic acid); 0 5 mole ( 82 grams) of tetrahydrophthalic 20 anhydride; 0 9 mole ( 85 grams) of maleic anhydride (unsaturated aliphatic dicarboxylic acid) to 1 5 moles ( 216 grams) of 1-4 cyclohexanedimethanol (alicyclic dihydric alcohol); 2 9 moles ( 301 grams) of neopentyl glycol (aliphatic dihydric alcohol); and 0 3 mole ( 87 grams) of tris ( 2 hydroxyethyl) isocyanurate (branching agent).

These ingredients were reacted by slow heating to 210 C, over a period of about 2 hours, 25 where an acid value of 50 was reached The reaction mixture was then cooled to 150 C Then, 1.8 moles ( 263 grams) of adipic acid (saturated aliphatic dicarboxylic acid) was added The reaction admixture was then slowly heated to 210 C where an acid value of about 55 was reached Total heating time was about 8 hours At this point 483 grams of butyl "Cellosolve" solvent was added This provided a polyester resin solution incorporating a major amount of 30 a mixture of aromatic dicarboxylic acid and tetrahydrophthalic anhydride and alicyclic polyol and having a mole ratio of OH/COOH of ( 1 5 + 2 9)/( 2 3 + 0 5 + 0 9 + 1 8) = 0 8, providing an acidic condition.

After the polyester resin cooled to 25 C, aqueous 25 % hexamethoxymethyl melamine and tap water was added in an amount effective to reduce the solids content of the polyester resin 35 to 60 wt % Dimethylethanolamine was added in an amount effective to increase the p H to about 8 5 The polyester resin dispersion was clear, had a viscosity of about 5,000 cps, and was found to be infinitely soluble in water.

Tests were then run to determine the gel time, cake hardness, weight loss, bond strength and temperature capability of the resin The results of these tests are shown in Table 1 below: 40 TABLE 1

GEL TIME WEIGHTLOSS % BOND STRENGTH 45 C 200 C 250 C 2 mils, 4 hrs cure 150 C 8 100 400 hrs 8 100 400 hrs 25 C 100 C min 7 % 15 % 24 % 13 % 23 % 26 % 261 bs 5 lbs.

50 Results of I E E No 57 Twisted Pair Test showed a thermal rating of 195 C to 200 C This provided a class H ( 180 C+ thermal rated) polyester insulating varnish with good bond strength and weight loss properties The polyester varnish was easily coated onto copper electrical conductors and cured to provide an excellent insulation.

55 EXAMPLE 2

A water dispersible polyester insulating resin was made using the same ingredients and method as in EXAMPLE 1, except that 513 grams of butyl "Cellosolve" was used and the neopentyl glycol was eliminated and substituted for by increasing the 1-4 cyclohexanedimethanol content up to 4 4 moles ( 634 grams) 60 The polyester resin had a mole ratio of OH/COOH of ( 4 4)/( 2 3 + 0 5 + 0 9 + 1 8) = 0 8, providing an acidic condition After the polyester resin cooled to 25 C, aqueous 25 % hexamethoxymethyl melamine and tap water was added in an amount effective to reduce the solids content of the polyester resin to 60 % Dimethylethanolamine was added in an amount effective to increase the p H to about 8 5 The polyester resin dispersion was clear; had a 65 4 1,603,149 4 viscosity of about 18,000 cps, and was infinitely soluble in water The results of tests are shown in Table 2 below:

TABLE 2

5 GEL TIME WEIGHTLOSS % BOND STRENGTH C 200 C 250 C 2 mils, 4 hrs cure 150 C 8 100 400 hrs 8 100 400 hrs 25 C 100 C 10 min 6 % 14 % 18 % 11 % 16 % 18 % 271 bs 7 lbs Results of I E E No 57 Twisted Pair Test showed a thermal rating of 195 C to 200 C This provided a class H ( 180 C+ thermal rated) insulating varnish with good bond strength and excellent weight loss properties 15 EXAMPLE 3

A water dispersible polyester insulating resin was made using the same ingredients and method as in EXAMPLE 1, except that the isophthalic anhydride content was increased to 2 6 moles ( 426 grams), the adipic acid content was decreased to 1 5 moles ( 219 grams) and 20 498 grams of butyl "Cellosolve" was used.

The polyester resin had a mole ratio of OH/COOH of ( 1 5 + 2 9/( 2 6 + 0 5 + 0 9 + 1 5) = 0 8, providing an acidic condition After the polyester resin cooled to 25 C, aqueous 25 % hexamethoxy methyl melamine and tap water was added in an amount effective to reduce the solids content of the polyester resin to 60 % Dimethylethanolamine was added in an amount 25 effective to increase the p H to about 8 5 The polyester resin dispersion was clear, had a viscosity of about 17,000 cps, and was infinitely soluble in water The results of tests are shown in Table 3 below:

TABLE 3 30

GEL TIME WEIGHTLOSS% BOND STRENGTH C 200 C 250 C 2 mils, 4 hrscure 150 C 35 8 100 400 hrs 8 100 400 hrs 25 C 100 C min 6 % 17 % 24 % 13 % 26 % 29 % 281 bs 9 lbs.

Results of I E E No 57 Twisted Pair Test showed a thermal rating of 195 C to 200 C This provided a class H ( 180 C+ thermal rated) insulating varnish still having acceptable gel times 40 and providing excellent bond strength and good weight loss properties.

An insulating varnish was made as described above except that 0 3 moles of trimethylol propane was substituted for tris ( 2 hydroxyethyl) isocyanurate as the branching agent The gel times and bond strengths were similar to those in Table 3 above, and the weight loss, while higher, was still acceptable 45 Similarly, other: aromatic dicarboxylic acids, such as phthalic acid and terephthalic acid and their anhydrides; unsaturated aliphatic dicarboxylic acids, such as fumaric acid; alicyclic dihydric alcohols, such as 1,2-cyclopentane diol and 1,2-cyclohexane diol; aliphatic dihydric alcohols, such as ethylene glycol; propylene glycol; 1,3-propane diol; 1, 2-butane diol; and 1,4-butane diol; saturated aliphatic dicarboxylic acids, such as succinic acid; glutaric acid; 50 pimelic acid; suberic acid; azelaic acid; sebacic acid and their anhydrides, branching agents, such as other hydroxy alkyl isocyanurates; glycerol; pentaerythritol, and insitol and other organic solvents, such as acetates; ketones and glycols, can be substituted for their corresponding materials used in the Examples.

55 EXAMPLE 4

As a comparative example, a polyester insulating resin was made having an OH/COOH mole ratio of 1 In this example no cross-linking agent was used, and the saturated aliphatic dicarboxylic acid (adipic acid) was added to the initial mix The resin was made by adding 1 mole ( 166 grams) of isophthalic acid; 1 mole ( 152 grams) of tetrahydrophthalic anhydride; 1 60 mole ( 98 grams) of maleic anhydride; 2 moles ( 288 grams) of 1-4 cyclohexanedimethanol; 2 moles ( 208 grams) of neopentyl glycol and 1 mole ( 146 grams) of adipic acid.

These ingredients were reacted by slow heating to 210 C where an acid value of about 45 to was reached The reaction mixture was then cooled to about 150 C and 386 grams of butyl cellosolve was added This provided a polyester resin having a mole ratio of OH/COOH of 65 1,603,149 1,603,149 ( 2 + 2)/( 1 + 1 + 1 + 1) = 1 0, providing a neutral condition.

After the polyester resin cooled to 25 C, aqueous 15 % hexamethoxy methyl melamine and tap water was added in an amount effective to reduce the solids content and dimethylethanolamine was added in an amount effective to increase the p H to about 8 5.

When the solids content was reduced to 48 %, the polyester resin dispersion became cloudy 5 Thus at an OH/COOH ratio of 1 0, major quantities of cyclic, thermally stable materials could not be incorporated into the polyester resin without a dramatic decrease in water solubility The addition of adipic acid in the initial mixing step also made the reaction less controllable.

Claims

WHATWECLAIMIS: 10

1 A method of producing a water dispersible polyester resin solution, which comprises esterifying a mixture of ingredients consisting essentially of:

(a) from 2 0 moles to 5 0 moles of an aromatic dicarboxylic acid, tetrahydrophthalic acid and mixtures thereof (b) from O 1 moleto 1 5 moles of an organic, unsaturated aliphaticdicarboxylic acid, 15 c) from 0 1 mole to 6 5 moles of an organic saturated aliphatic dicarboxylic acid, d) from 1 O mole to 5 O mole of an alicyclic dihydric alcohol, e) O mole to 5 O moles of an organic, aliphatic dihydric alcohol, f) from 0 3 mole to 1 2 moles of tris ( 2 hydroxy alkyl) iso cyanurate where alkyl is from 2 to 6 carbon atoms or a polyhydric alcohol containing more than two hydroxy groups per 20 molecule and (g) an amount of organic solvent effective to provide a solution of from 50 wt % to 90 wt.% solids content, and finally, diluting the polyester resin solution with a partially methylated melamine formaldehyde resin, and adding an organic aliphatic amine in an amount effective to provide a p H of from 8 to 9, wherein the esterification reaction is 25 continued until the acid value drops to between 45 and 65, and wherein the mole ratio of OH/COOH = 0 30 to O 90.

2 A method according to claim 1 wherein ingredients (a), (b), (d), (e) and (f) are reacted until the acid value drops to between 45 and 65 and then ingredient (c) is added and wherein the viscosity of the polyester resin solution is from 4000 cps to 20000 cps at 25 C 30

3 A method according to claim 1 or claim 2, wherein the aromatic dicarboxylic acid is at least one of phthalic acid; isophthalic acid; terephthalic acid and their anhydrides; the unsaturated aliphatic dicarboxylic acid is at least one of maleic acid; fumaric acid and their anhydrides; the saturated aliphatic dicarboxylic acid is at least one of adipic acid; succinic acid; glutaric acid; pimelic acid; suberic acid; azelaic acid; sebacic acid and their anhydrides; 35 the alicyclic dihydric alcohol is at least one of 1,4-cyclohexane dimethanol; 1,2-cyclopentane diol and 1,2-cyclohexane diol; the aliphatic dihydric alcohol is at least one of neopentyl glycol; ethylene glycol; propylene glycol; 1-3-propanediol; 1,2-butane diol and 1,4-butane diol.

4 A method according to claim 1, 2 or 3, wherein the organic compound of (f) is at least 40 one of tris ( 2 hydroxy ethyl) isocyanurate, trimethylol propane, glycerol, pentaerythritol, dipentaerythritol, trimethylol ethane, sorbitol, erythritol and inositol and the organic solvent is at least one of ethylene glycol monoalkyl ethers, ethylene glycol mono acetates, ketones and glycols having flash points of over 150 C, and the amine, added in the last step to adjust the p H, is at least one of triethanol amine; triethylamine; 2 amino-2methyl-1 propanol and 45 dimethylethanol amine.

A method according to any one of claims 1 to 4 which comprises esterifying a mixture of ingredients, by the steps of adding the ingredients (a), (b), (d), (e) and (f) of claim 1, heating, in an esterification process, until the acid value of the mixture drops to between 45 and 65, adding ingredient (c) of claim 1, heating, in an esterification process, to form a 50 polyester resin solution, wherein the mole ratio of OH/COOH = 0 30 to 0 90, while maintaining the acid value between 45 and 65, and adding an amount of organic solvent effective to provide a solution of from 50 wt % to 90 wt % solids content.

6 A method according to any of claims 1 to 6, wherein the organic solvent is at least one of ethylene glycol monobutyl ether and diethylene glycol monobutyl ether and the amine 55 added in the last step to adjust the p H is at least one of triethanol amine; triethylamine; 2 amino-2-methyl-1 propanol and dimethylethanol amine.

7 A method of producing a water dispersible polyester resin solution substantially as described herein with particular reference to Examples 1 to 3 of the foregoing Examples.

:5 6 1,603,149 6

8 Water dispersible polyester resin solutions when made by the method of any of claims 1 to 7.

9 Electrical conductors coated with a polyester when made by the method of any of claims 1 to 7 and in a cured condition.

RONALD VAN BERLYN 5 Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1981.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.